Apparatus, systems and methods for detecting and transmitting sensory data over a computer network

ABSTRACT

A vapor sensing device that is sufficiently small and lightweight to be handheld, and also modular so as to allow the device to be conveniently adapted for use in sensing the presence and concentration of a wide variety of specified vapors. The device provides these benefits using a sensor module that incorporates a sample chamber and a plurality of sensors located on a chip releasably carried within or adjacent to the sample chamber. Optionally, the sensor module can be configured to be releasably plugged into a receptacle formed in the device. Vapors are directed to pass through the sample chamber, whereupon the sensors provide a distinct combination of electrical signals in response to each. The sensors of the sensor module can take the form of chemically sensitive resistors having resistances that vary according to the identity and concentration of an adjacent vapor. These chemically sensitive resistors can each be connected in series with a reference resistor, between a reference voltage and ground, such that an analog signal is established for each chemically sensitive resistor. The resulting analog signals are supplied to an analog-to-digital converter, to produce corresponding digital signals. These digital signals are appropriately analyzed for vapor identification. The device can then subsequently transmit the digital signals over a computer network, such as the Internet, for analysis at a remote location.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.09/518,179, filed Mar. 2, 2000, allowed, which application claims thebenefit of U.S. Provisional Application Ser. No. 60/122,688, filed Mar.3, 1999, U.S. application Ser. No. 09/271,873, filed Mar. 18, 1999, U.S.Provisional Application Ser. No. 60/162,683, filed on Nov. 1, 1999 andU.S. Provisional Application Ser. No. 60/164,022, filed on Nov. 4, 1999.All of these applications are incorporated herein by reference in theirentirety for all purposes.

BACKGROUND OF THE INVENTION

This invention generally relates to the detection and transmission ofsensory data. More particularly, the present invention relates to anapparatus for detecting and transmitting sensory data of analytes fromone portable handheld electronic nose (e-nose) to another for analyticpurposes.

Techniques and devices for detecting a wide variety of analytes influids such as vapors, gases and liquids are well known. As used hereinthe term “fluid” means gases, vapors and liquids. An electronic nose isan instrument used to detect vapors or chemical analytes in gases,solutions, and solids. In certain instances, the electronic nose is usedto simulate a mammalian olfactory system. In general, an electronic noseis a system having an array of sensors that are used in conjunction withpattern-recognition algorithms. Using the combination of chemicalsensors, which produce a fingerprint of the vapor or gas, therecognition algorithms can identify and/or quantify the analytes ofinterest. The electronic nose is thus capable of recognizing unknownchemical analytes, odors, and vapors.

In practice, an electronic nose is presented with a substance such as anodor or vapor, and the sensor converts the input of the substance into aresponse, such as an electrical response. The response is then comparedto known responses that have been stored previously. By comparing theunique chemical signature of an unknown substance to “signatures” ofknown substances, the unknown analyte can be determined. A variety ofsensors can be used in electronic noses that respond to various classesof gases and odors.

A wide variety of commercial applications are available for electronicnoses including, but not limited to, environmental toxicology andremediation, biomedicine, such as microorganism classification ordetection, material quality control, food and agricultural productsmonitoring, heavy industrial manufacturing, ambient air monitoring,worker protection, emissions control, and product quality testing. Manyof these applications require a portable device because they are locatedin the field or because they have an inaccessible location for largerlaboratory models. Conventionally, most of the electronic noses havebeen large cumbersome laboratory models incapable of being used in thefield and pilot plant applications. If available, a portable or handhelddevice would provide the portability required for pilot plant and fieldlocations. Unfortunately, the portable chemical detectors that have beendeveloped thus far have many limitations that have kept them from beingwidely accepted.

For instance, U.S. Pat. No. 5,356,594, which issued to Neel et al.,discloses a portable volatile organic monitoring system designed for usein detecting fugitive emissions. The device includes a bar code readerfor inventorying the emission site. The device contains a single sensorresponsive to ionized gas, however the device only detects the amount(i.e., concentration) of the volatile compound. The device is incapableof identifying the volatile organic compound. Thus, the device is merelya vapor amount logger and not a portable electronic nose. As such, theuser is required to know the identity of the vapor being quantitated orthis information must be stored elsewhere.

Another example of a portable device is disclosed in U.S. Pat. No.4,818,348 issued to Stetter. Although this portable device is moresophisticated than the previous example, it still has many limitations.In this instance, the device is capable of identifying a gas or vapor,but the applications are quite limited because of sensor architecturallimitations. The sensors making up the array are permanently fixed, andthus, the number and variety of analytes and gases that the device iscapable of identifying is quite small. Moreover, because the analyte orvapor being identified interacts with each sensor of the array in adifferent amount, the reproducibility and stability of the device isquite limited. These limitations affect the device's accuracy inidentifying unknowns.

Concurrent with the development of better detection techniques fordetecting analytes, there is an emerging need to develop methods anddevices to efficiently transmit the collected sensory data for swiftanalysis. Under some prior customary practices, the sensory data werefirst captured and then physically transported back to a laboratory orsome other designated facility for subsequent analysis. Very often,analyses on these data would not be performed until a substantial periodof time had elapsed and consequently their results would not beavailable for hours, days or even weeks.

Timely transmission and analysis of sensory data for detected analyteshave tremendous applications in a variety of areas. There are manyinstances where it is desirable to obtain results on the analysis of thesensory data in a timely manner. For example, in a hospital/medicalenvironment, it would be greatly beneficial if data collected from apatient can be transmitted quickly to a laboratory to determine thecause of the patient's ailments thereby allowing the doctors toprescribe the necessary treatment without any undue delay. In a similarexample, medical and other related data from home monitoring devices canbe collected and transmitted swiftly to the appropriate hospitals and/orauthorities to allow them to provide better response to homeemergencies. In another example, in environments where the presence ofcertain substances can potentially lead to dangerous conditions, such asa gas leak in a foundry or a home, the swift transmission of sensorydata for analysis can very well preempt an impending disaster. Clearly,there are many other situations that one could think of where theefficient transmission of sensory data will generate tremendousbenefits. Hence, it would be desirable and beneficial to create a methodand system that is capable of timely transmitting sensory data foranalysis.

In addition to the need to have timely transmission of sensory data,there is a need to provide easy access to the collective data compiledfor the known analytes. The results of any detection analysis are onlyas good as the data that are available for comparison. At the presenttime, various analytes have been identified and data therefor have beencompiled and stored all over the world. Perhaps, due to the voluminousamount of data that are available, these data are generally notcentralized in any one particular depository but are instead separatelystored at different facilities. The segregation of these data,therefore, renders a complete and accurate analysis more difficult.Hence, it would be desirable to have a method and system that is capableof providing better access to these available data thereby allowing moreaccurate analyses to be performed. The present invention fulfills theseand other needs by providing a method and system of detecting,transmitting, storing and retrieving sensory information over a computernetwork.

SUMMARY OF THE INVENTION

The invention relates generally to a sensing apparatus (also referred toas an electronic-nose or e-nose device). The apparatus is compact and,in certain embodiments, configured to be a handheld device. The e-nosedevice can be used to measure or identify one or more analytes in amedium such as vapor, liquid, gas, solid, and others. Some embodimentsof the e-nose device includes at least two sensors (i.e., an array ofsensors) and, in some other embodiments, about two to about 200 sensorsin an array and preferably about four to about 50 sensors in the array.The device of the present invention can detect sensory data such asphysical, chemical, taste, olfaction, optical olfaction, opticalparameters or combinations thereof.

The e-nose device is versatile and meets the needs of a wide range ofapplications in various industries. In certain embodiments, the deviceis designed as a slim handheld, portable device with variousfunctionalities. In another embodiments, the device is designed as aportable field tool with full functionality. The e-nose device typicallyincludes an internal processor for processing samples and reportingdata. Optionally, the device can be coupled to a computer, such as apersonal computer, for access to set-up and advanced features and fortransfer of data files.

In some embodiments, sections of the e-nose device are disposed withinmodules that can be installed, swapped, and replaced as necessary. Forexample, the sensor module, sampling wand or nose, battery pack, filter,electronics, and other components, can be modularized, as describedbelow. This modular design increases utility, enhances performance,reduces cost, and provides additional flexibility and other benefits.

A specific embodiment of the invention provides a handheld sensingapparatus that includes a housing, a sensor module, a sample chamber,and an analyzer. The sensor module and the analyzer mount in thehousing. The sensor module includes at least two sensors that provide adistinct response to a particular test sample. The sample chamber isdefined by the housing or the sensor module, or both, and incorporatesan inlet port and an outlet port. The sensors are located within oradjacent to the sample chamber. The analyzer is configured to analyze aparticular response from the sensors and to identify or quantify, basedon the particular response, analytes within the test sample.

In a variation of the above embodiment, the housing of the handheldsensing apparatus includes a receptacle, and the sensor module isremovably mounted in the receptacle of the housing. In this embodiment,the sensor module can include one or more sensors.

Another specific embodiment of the invention provides a sensor moduleconfigured for use with a sensing apparatus. The sensor module isdisposed within a housing that defines a receptacle. The sensor moduleincludes a casing, a sample chamber, an inlet port, an outlet port, atleast two sensors, and an electrical connector. The casing is sized andconfigured to be received in the receptacle of the sensing apparatus.The inlet port is configured to be releasably engageable with a portconnection of the sensing apparatus when the sensor module is receivedin the receptacle. The inlet port receives a test sample from thesensing apparatus and directs the test sample to the sample chamber. Theoutlet port is configured to discharge the test sample from the samplechamber. The sensors are located within or adjacent to the samplechamber and are configured to provide a distinct response when exposedto one or more analytes located within the sample chamber. Theelectrical connector is configured to be releasably engageable with amating electrical connector of the sensing apparatus when the sensormodule is received in the receptacle. The electrical connector transmitsthe characteristic signals from the sensors to the sensing apparatus.

Yet another specific embodiment of the invention provides a handheldsensing apparatus for measuring the concentration of one or moreanalytes within a sample chamber. The sensing apparatus includes two ormore chemically sensitive resistors, conditioning circuitry, ananalog-to-digital converter (ADC), and an analyzer. Each chemicallysensitive resistor has a resistance that varies according to aconcentration of one or more analytes within the sample chamber. Theconditioning circuitry couples to the chemically sensitive resistors andgenerates an analog signal indicative of the resistance of theresistors. The ADC couples to the conditioning circuitry and provides adigital signal in response to the analog signal. The analyzer couples tothe ADC and determines, based on the digital signal, the identity orconcentration of the analyte(s) within the sample chamber.

Yet another embodiment of the invention provides a portable, handheldvapor sensing apparatus that includes a sensor module incorporating aplug-in array of vapor sensors that provide different electricalresponses to one or more distinct vapors. The apparatus includes ahandheld housing, and the sensor module optionally can be removablymounted in a receptacle formed in the housing. The sensor module definesa sample chamber to which the array of vapor sensors is exposed. Thesample chamber incorporates a vapor inlet and a vapor outlet, and a pumpis mounted within the housing for directing a vapor sample from thevapor inlet through the sample chamber to the vapor outlet. A monitoringdevice also is mounted within the housing, for monitoring the electricalresponses of the array of vapor sensors and for producing acorresponding plurality of sensor signals. In addition, an analyzer ismounted within the housing for analyzing the plurality of sensor signalsand to identify any vapor sample directed through the sample chamber bythe pump.

In more detailed features of the invention, the handheld vapor sensingapparatus further includes a controller or processor configured tocontrol the pump either to direct one of a plurality of reference vaporsor an unknown vapor sample through the sample chamber. When thecontroller is controlling the pump to direct one of the plurality ofreference vapors through the sample chamber, the monitoring devicemonitors the electrical responses of the array of vapor sensors toproduce a reference signature. Thereafter, when the controller iscontrolling the pump to direct the unknown vapor sample through thesample chamber, the monitoring device monitors the electrical responsesof the array of vapor sensors to produce a vapor sample signature. Theanalyzer then compares the vapor sample signature with a plurality ofreference signatures, to identify the unknown vapor sample.

In other more detailed features of the invention, the sample chamber ofthe handheld vapor sensing apparatus is defined by the sensor module,alone, and it is sealed from the external environment except for thevapor inlet and the vapor outlet. In addition, each sensor moduleincludes a plurality of first electrical connectors and a plurality ofdevices of substantially identical size and shape, the devices togethercarrying the array of vapor sensors and each including a secondelectrical connector along one edge thereof, for mating engagement withone of the first electrical connectors.

In yet further more detailed features of the invention, the handheldvapor sensing apparatus further includes an electrical circuit thatcontrols the temperature of the array of vapor sensors. In addition,when the sensor module is configured to be removably mounted in thehousing receptacle, the module carries an identifier for identifying thevapor sensors it carries, and the monitor further is configured to readthe identifier carried by the sensor module received in the receptacle.

In an embodiment, the sensors are implemented with chemically sensitiveresistors having resistances that vary according to the concentration ofone or more prescribed vapors within the sample chamber. Thesechemically sensitive resistors are each connected in series with aseparate reference resistor, between a reference voltage and ground,such that an analog signal is established for each chemically sensitiveresistor. An analog-to-digital converter is responsive to these analogsignals and to the reference voltage, to produce digital output signalsindicative of the resistances of the various chemically sensitiveresistors. A multiplexer can be included for sequentially connecting thevarious analog output signals to the analog-to-digital converter. Inaddition, an analyzer is responsive to the digital output signals, todetermine the presence and/or concentration of one or more prescribedvapors within the sample chamber.

In yet another embodiment, the e-nose device is used to detect andcapture analyte data and subsequently transmit such data over a computernetwork to a remote location for analysis.

In another embodiment, the present invention provides a system foracquiring sensory data over a wide area network of computers. The systemincludes a network and a sensory device, such as a handheld sensingdevice, coupled to the network. The system also includes a communicationinterface coupled to the sensory device that is configured tocommunicate with the network.

In still yet another embodiment, the present invention relates to acomputer program product for transmitting sensory data in a networkedenvironment. Generally, the networked environment includes a sensorydevice, such as the handheld sensing device, connected to a remotelocation by a network. The computer program product includes code fortransmitting a sensory data file from a sensory device to a remotelocation. The computer program product also includes code for receivingthe sensory data file at the remote location. The computer programproduct can also include code for processing the sensory data file atthe remote location for a diagnostic purpose. A computer readablestorage medium for holding the codes is also included in the computerprogram product.

In another feature, the present invention provides a use of a handheldsensing apparatus with an interface for communication to the outsideworld, preferably via a network. A suitable network includes, but is notlimited to, a wide area network, a local-area network, an intranet, aworldwide computer network, and the Internet. The communication ispreferably the transmission of sensory information including, but notlimited to, physical data, chemical data, taste data, olfaction data,optical olfaction data, optical parameters or combinations thereof. Incertain aspects, the network comprises wireless components.

Other features and advantages of the present invention should becomeapparent from the following description of the preferred embodiments,taken in conjunction with the accompanying drawings, which illustrate,by way of example, the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a pictorial view of an operator using an e-nose device;

FIGS. 2A and 2B show a top and bottom perspective view, respectively, ofan embodiment of an e-nose device;

FIG. 3A shows six perspective views of an embodiment of another e-nosedevice;

FIG. 3B shows four different embodiments of noses for the e-nose deviceof FIG. 3A;

FIG. 4 shows a diagram of an embodiment of the subsystems of the e-nosedevice;

FIG. 5 shows an exploded perspective view of some of the majorcomponents of the e-nose device of FIG. 2A;

FIGS. 6A and 6B show an exploded perspective view of two embodiments ofthe mechanical subsystem of the e-nose device;

FIG. 6C shows an exploded perspective view of an embodiment of a filter;

FIGS. 7A-7B show a perspective view and a top sectional view,respectively, of an embodiment of a sensor module that includes foursensor devices mounted within two sample chambers;

FIG. 7C shows a perspective view of the sensor array device;

FIGS. 8A and 8B show a perspective view and a top sectional view,respectively, of an embodiment of another sensor module that includesfour plug-in sensor devices within a single sample chamber;

FIGS. 9A through 9C show a perspective view, a side sectional view, anda partial top sectional view, respectively, of an embodiment of a yetanother sensor module that includes a single sensor array device;

FIG. 10 shows various accessories for the e-nose device;

FIG. 11 shows a perspective view of an e-nose device shown mountedvertically in an electrical charging station and coupled to a hostcomputer;

FIG. 12A shows a diagram of an embodiment of the electrical circuitrywithin the e-nose device;

FIG. 12B shows an embodiment of a voltage divider network used tomeasure the resistance of a chemically sensitive resistor;

FIG. 12C shows a diagram of another embodiment of the electricalcircuitry within the e-nose device;

FIGS. 13A through 13G show an embodiment of suitable flowcharts of thefunctional steps performed by the e-nose device in implementing themeasurement and analysis procedures;

FIGS. 14A through 14C show a diagram of an embodiment of the menuselection for the e-nose device;

FIG. 15 shows a graph of a principal component analysis of the responsesto a series of esters using the handheld apparatus of the presentinvention;

FIG. 16 is a simplified schematic block diagram showing one mode ofoperation of the present invention;

FIG. 17 is a simplified schematic block diagram showing another mode ofoperation of the present invention;

FIG. 18 is a simplified schematic block diagram showing yet another modeof operation of the present invention;

FIG. 19 is a simplified flow diagram showing the process of encoding thedata by the e-nose device; and

FIG. 20 is a simplified flow diagram showing the process of decoding thedata sent by the e-nose device.

DETAILED DESCRIPTION OF THE INVENTION AND SPECIFIC EMBODIMENTS

FIG. 1 shows a pictorial view of an operator using an e-nose device 100.In the embodiment shown in FIG. 1, e-nose device 100 is a portable,handheld instrument for sensing the presence of one or more specifiedanalytes in a particular sample. As use herein, a sample is a unit of avapor, liquid, solution, gas, solid, or other forms, and mixturesthereof, of a substance being analyzed. Thus, a sample includes chemicalanalytes, odors, vapors, and others. The sample can comprise a singleanalyte or a plurality of analytes. In FIG. 1, e-nose device 100 is usedfor industrial monitoring and detection, i.e., to identify and quantifynoxious gas escaping from an industrial valve assembly. E-nose device100 can also be used for many other applications, as enumerated below.

FIG. 2A shows a top perspective view of an embodiment of an e-nosedevice 100 a. E-nose device 100 a includes an elongated housing 110 ahaving a lower end sized to be conveniently grasped and supported by thehand of an operator. A display 120 a and several push-button controlswitches 122 a through 122 c are located on the housing's topside, forconvenient viewing and access by the operator. Push-button switches 122are used to control the device during its various operating modes.Display 120 a displays information about such operating modes and theresults of the device's sensing.

A tubular sampling wand 130 a and an exhaust port 134 are provided torespectively receive and discharge samples to be analyzed. The samplingwand is also referred to as a nose or snout. A plug-in sensor module 150a is shown installed in its socket located at the base of e-nose device100 a. The operation of sensor module 150 a is described in detailbelow. An electrical connector 126 located at the lower end of housing110 a allows for communication with a host computer, and electricalcontacts 128 allow for application of external power that could be usedto operate the e-nose device and to recharge the rechargeable batterywithin the e-nose device.

FIG. 2B shows a bottom perspective view of e-nose device 100 a. As shownin FIG. 2B, one sampling wand 130 a 1 is secured in place and a secondsampling wand 130 a 2 is being stored in an elongated recess 162 locatedon the underside of device 100 a. Sampling wand 130 a can be stored whennot in use and is releasably secured in place by a pair of spring clips164 a and 164 b. Plug-in sensor module 150 a is shown removed from itssocket 152.

FIG. 3A shows six perspective views of an embodiment of another e-nosedevice 100 b. E-nose device 100 b includes a nose 130 b, a display 120b, and a set of buttons 124. Similar to e-nose device 10 a, nose 130 bin e-nose device 100 b is removably coupled to a housing 110 b. A set ofconnectors 127 allows for interconnection with external devices andsystems.

FIG. 3B shows four different embodiments of noses 130 c through 130 f.As these examples illustrate, the noses can be specially dimensioned forimproved performance in specific applications.

FIG. 4 shows a diagram of an embodiment of the subsystems of e-nosedevice 100. The upper half of FIG. 4 shows an electrical subsystem 410and the lower half shows a (ie., substantially mechanical) subsystem 412that processes test samples. Within subsystem 412, a test sample isreceived via a nose 430 and provided to a manifold 440. Similarly, areference or background sample is received via an intake port 432 andprovided through a filter 436 to manifold 440. Filter 436 can be a blankfilter, a carbon filter, or others. Manifold 440 directs the test andclean samples to a solenoid 444 that selects one of the samples as thesolenoid output. The selected sample is directed through manifold 440 toa sensor module 450. Sensor module 450 includes at least two sensorsthat detect analytes in the selected sample. Sensor module 450 generatesa signal (or a “signature”) indicative of the detected analytes andprovides this signal to electrical subsystem 410. The selected sample isthen provided from sensor module 450, through manifold 440, furtherthrough a pump 460, and to an exhaust port 434. Nose 430, intake port432, exhaust port 434, and sensor module 450 in FIG. 4 generallycorresponds to nose 130 a, intake port 132, exhaust port 134, and sensormodule 150 a in FIG. 2A, respectively.

FIG. 4 shows an embodiment of subsystem 412. Many other components anddevices (not shown) can also be included in subsystem 412. Further, itis not necessary for all of the components and devices shown in FIG. 4to be present to practice the present invention. Moreover, thecomponents and devices may be arranged in different configurations thanthat shown in FIG. 4. For example, pump 460 can be coupled to the outputof solenoid 444 instead of exhaust port 434.

As shown by the embodiment in FIG. 4, electrical subsystem 410 includesa PCB assembly 470 that interconnects with a display 472, a battery pack474, a keypad 476, an analog port 478, an interface 480, and switches482 a and 482 b. Display 474 can be a liquid crystal display (LCD) andcan include backlight controllers drivers and (optionally) a touchpad. Acontrast adjustment mechanism can be provided to adjust display 472.Electrical subsystem 410 is described in further detail below.

FIG. 5 shows an exploded perspective view of some of the majorcomponents of e-nose device 100 a. FIG. 5 also depicts an embodiment ofa subsystem 412 a. In use, e-nose device 100 a is configured to draw ina test sample (i.e., in a vapor, liquid, or gas medium) from a locationof interest (i.e., the space adjacent to the valve assembly in FIG. 1)through sampling wand 130a, and to direct this sample through plug-insensor module 150 a installed in socket 152. After passing throughsensor module 150 a, via ports 512 a and 512 b, the sample is directedoutwardly through exhaust port 134 at the side of the device. Atspecified times during the device's various operating modes, a referencesample is drawn into the device via intake port 132, directed throughsensor module 150 a, and discharged through exhaust port 134.

The device's housing 111 a can be formed of molded plastic and includesa lower half 112 a and an upper half 112 b. Many of the device'sinternal components are conveniently and efficiently mounted on aprinted circuit board (PCB) 510 that extends substantially across thedevice's interior volume. Display 120 a is mounted at the top end of thePCB, where it is visible through an aperture 520 formed in the housing'supper half 112 a. The push-button control switches 122 a through 122 care mounted below display 120 a, in positions where they can extendthrough correspondingly sized openings 522 formed in the housing's upperhalf 112 a.

A valve assembly 540 mounted on the underside of PCB 510 receives thetest sample drawn into e-nose device 100 a via sampling wand 130 a andthe reference sample via intake port 132. The test sample is directedfrom sampling wand 130 a to the valve assembly via a tube 532, and theclean sample is directed from intake port 132 to the valve assembly viaa tube 534. Valve assembly 540 is configured to select from one of twosources, coming via either sampling wand 130 a or intake port 132. Fromvalve assembly 540, the sample from the selected source is directed viaa tube 536 through socket 152 to sensor module 150 a, which is locatedon the top side of the PCB. After analysis by the sensor module, thesample is directed through a tube 538 to a pump 560 located on theunderside of the PCB. Finally, the sample is discharged from the deviceby directing it from pump 560 through a tube 562 to exhaust port 134.Alternatively, pump 560 could be located in the path between valveassembly 540 and sensor module 150 a. In an embodiment, the componentscoming in contact with the sample being processed (including tubes 532,534, 536, 538, and 562) are formed of an inert or non-corrosivematerial, such as Teflon, stainless steel, or Teflon-coated metal. Valveassembly 540 in FIG. 5A generally corresponds to manifold 440 andsolenoid 444 in FIG. 4, and pump 560 corresponds to pump 460.

In certain aspects, the handheld apparatus of the present inventionincludes an optional preconcentrator. Advantageously, with certainanalytes, such as high vapor pressure analytes, the analyte isconcentrated on an absorbent. The preconcentrator can be used toincrease the concentration of analytes in the test sample.Preconcentrators are traps composed of an adsorbent material. In use, anadsorbent material attracts molecules from the gas sample that areconcentrated on the surface of the adsorbent. Subsequently, the sampleis “desorbed” and analyzed. Suitable preconcentrator materials include,but are not limited to, a polymeric adsorbent material, unsilanizedglass wool, Teflon or porus glass fiber, and the like. The adsorbentmaterial is packed in a tube, such as a steel tube.

During use, the sample is drawn into the trap that concentrates thecomponents of interest. In some instances, the tube is wrapped with awire through which current can be applied to heat and thus, desorb thetest sample. The sample is thereafter transferred into the modulecontaining the sensors.

The preconcentrator can be disposed in various locations between thesampling wand and the sensor module. In certain aspects, thepreconcentrator can be placed in the nozzle of the device or,alternatively, in the manifold or other convenient location upstream ofthe sensor module. For example, the preconcentrator can be disposedwithin valve assembly 540, or housed in a unit coupled to the valveassembly (not shown in FIG. 5). Optionally, additional valves can beinstalled in the device facilitating preconcentration and sensing.

Suitable commercially available adsorbent materials used inpreconcentrators include, but are not limited to, Tenax TA, Tenax GR,Carbotrap, Carbopack B and C, Carbotrap C, Carboxen, Carbosieve SIII,Porapak, Spherocarb, and combinations thereof. Preferred adsorbentcombinations include, but are not limited to, Tenax GR and Carbopack B;Carbopack B and Carbosieve SIII; and Carbopack C and Carbopack B andCarbosieve SIII or Carboxen 1000. Those skilled in the art will know ofother suitable absorbents.

Operation of e-nose device 100 is controlled by a processor disposedwithin an electronic unit 570 mounted on the topside of PCB 510.Electronic unit 570 further includes one or more memory devices to storeprogram codes, data, and other configuration information. The electronicunit and control of the e-nose device is described in further detailbelow.

FIG. 6A shows an exploded perspective view of an embodiment of anothersubsystem 412 b. Subsystem 412 b includes a manifold 640 a mounted on amanifold seal plate 642 a. Manifold 640 a includes fittings for mountinga valve (or solenoid) 644 a, fittings for mounting a sensor module 650a, and fittings for mounting a pump 660 a. The sample is directedbetween the various sub-assemblies (e.g., valve 644 a, sensor module 650a, and pump 660 a) via cavities located within manifold 640 a and tubes(not shown). Manifold 640 a further includes a recessed opening 648 aconfigured to receive a filter 636 a.

FIG. 6B shows an exploded perspective view of an embodiment of yetanother subsystem 412 c. Subsystem 412 c includes a manifold 640 bmounted on a manifold seal plate 642 b via a seal plate gasket 644 b.Manifold 640 b includes fittings for mounting a valve (or solenoid) 644b and fittings for mounting a pump 660 b. A filter cartridge 646 bmounts on top of manifold 640 b and includes a recessed opening 648 bconfigured to receive a filter element. A filter cover 636 b enclosesrecessed opening 648 b and an O-ring 638 b provides a seal for thefilter. The sample is directed between the various sub-assemblies (e.g.,valve 644 b and pump 660 b) via cavities located within manifold 640 band tubes (not shown).

Filter 636, manifold 640, valve 644, sensor module 650, and pump 660 inFIGS. 6A and 6B correspond to filter 436, manifold 440, solenoid 444,sensor module 450, and pump 460 in FIG. 4, respectively.

FIG. 6C shows an exploded perspective view of an embodiment of a filter.The filter includes a circular base unit 680 having an outer wall 682and an inner wall 686. A set of small-size openings is disposed withinouter wall 682 for drawing in samples into the filter. A inner circularring 684 covers inner wall 686 that has disposed therein another set ofsmall size openings, for drawing the samples from the filter. A filtermaterial (e.g., charcoal) 688 for filtering the samples is disposedwithin the space between the outer and inner walls. O-ring 638 b is usedto seal the filter.

FIGS. 7A-7B show a perspective view and a top sectional view,respectively, of an embodiment of a sensor module 150 b that includesfour sensor devices mounted within two sample chambers 710 a and 710 b.In FIGS. 7A and 7B, sensor module 150 b is depicted as being configuredfor non-removable securement to the PCB, but which alternatively couldbe configured as a plug-in module such as sensor module 150 a. In aspecific embodiment, sensor module 150 b incorporates four plug-insensor array devices 720, each including eight chemically sensitivesensors 740. Sensor module 150 b can include greater or fewer number ofsensor array devices, and each sensor array device can include greateror fewer number of sensors. The four sensor array devices 720 aremounted vertically in pairs on a board 730. A cover 732 having a pair ofelongated recesses is secured over board 730 so as to define twoseparate sample chambers 710 a and 710 b, one for each pair of sensorarray devices 720. Sensor array devices 720 are of similar shape andsize, and each can be received in any one of the four connectors, orreceptacles 722, formed in board 730.

FIG. 7C is a perspective view of one sensor array device 720. In anembodiment, each sensor array device 720 includes an array of eightchemically sensitive sensors 740, each providing a particularcharacteristic response when exposed to a test sample carrying analytesto be sensed. In an embodiment, the sensors are implemented usingchemically sensitive resistors that provide particular resistances whenexposed to a test sample. A multi-contact electrical connector 742 islocated along the lower edge of sensor array device 720 and isconfigured for insertion into one of four receptacles 722. Suitablesensor arrays of this kind are disclosed in U.S. Pat. No. 5,571,401,issued in the names of Nathan S. Lewis et al., entitled “Sensor Arraysfor Detecting Analytes in Fluids,” and incorporated herein by reference.Those of ordinary skill in the art will appreciate that variousalternative chemically sensitive sensors or devices could also be used.

As shown in FIG. 7B, the test sample is directed through sensor module150 b from an inlet port 750, through two sample chambers 710 a and 710b, and to an outlet port 760. Sensor array devices 720 are arranged suchthat the test sample moves laterally across the exposed chemicallysensitive sensors. Baffles 762 and 764 are located at the respectiveleading and trailing ends of each sample chamber, to assist in providingan efficient flow pattern, as shown in FIG. 7B.

FIGS. 8A and 8B show a perspective view and a top sectional view,respectively, of an embodiment of another sensor module 150 c thatincludes four plug-in sensor devices 820 within a single cavity orsample chamber 810. Sample chamber 810 is defined, in part, by a cover832 that is secured over a board 830. This configuration can be designedto provide a longer dwell time for the test sample within the samplechamber, which can be advantageous in some applications.

Like the chemically sensitive sensors included on sensor array devices720 in FIGS. 7A and 7B, the chemically sensitive sensors included onsensor array device 820 in FIGS. 8A and 8B can take the form of thearrays disclosed in U.S. Pat. No. 5,571,401. Those of ordinary skill inthe art will appreciate that various alternative chemically sensitivesensors or devices could also be used.

FIGS. 9A and 9B show a perspective view and a side sectional view,respectively, of an embodiment of yet another sensor module 150 d thatincludes a single sensor array device 920. In a specific embodiment,sensor array device 920 includes 32 chemically sensitive sensorsarranged in a two-dimensional grid and is mounted in a generallyhorizontal orientation on a socket 922. Of course, sensor array device920 can include greater or fewer number of sensors. A screen 924 (seeFIGS. 9B and 9C) overlays sensor array device 920 and, in an embodiment,includes a separate opening 926 overlaying each chemically sensitivesensor. Screen 924 is attached to a cover 932, the combination of whichdefines an upper chamber 934 and a lower chamber 936. As shown in FIG.9B, the test sample being analyzed is directed from an inlet port 950 toupper chamber 934, and from there through screen 924 to lower chamber936 where it passes across the chemically sensitive sensors. The testsample then exits through an outlet port 960. Again, it will beappreciated that various alternative chemically sensitive sensors anddevices could also be used.

The e-nose device of the invention includes an array of sensors and, incertain instances, the sensors as described in U.S. Pat. No. 5,571,401are used. Various sensors suitable for detection of analytes include,but are not limited to: surface acoustic wave (SAW) sensors; quartzmicrobalance sensors; conductive composites; chemiresitors; metal oxidegas sensors, such as tin oxide gas sensors; organic gas sensors; metaloxide field effect transistor (MOSFET); piezoelectric devices; infraredsensors; sintered metal oxide sensors; Pd-gate MOSFET; metal FETstructures; metal oxide sensors, such as a Tuguchi gas sensors;phthalocyanine sensors; electrochemical cells; conducting polymersensors; catalytic gas sensors; fiber optical chemical sensors; organicsemiconducting gas sensors; solid electrolyte gas sensors; piezoelectricquartz crystal sensors; and Langmuir-Blodgett film sensors.

In a preferred embodiment, the sensors of the present invention aredisclosed in U.S. Pat. No. 5,571,401, incorporated herein by reference.Briefly, the sensors described therein are conducting materials andnonconducting materials arranged in a matrix of conducting andnonconducting regions. The nonconductive material can be a nonconductingpolymer such as polystyrene. The conductive material can be a conductingpolymer, carbon black, an inorganic conductor and the like. The sensorarrays comprise at least two sensors, typically about 32 sensors, and incertain instances 1000 sensors. The array of sensors can be formed on anintegrated circuit using semiconductor technology methods, an example ofwhich is disclosed in PCT patent application Ser. No. WO99/08105,entitled “Techniques and Systems for Analyte Detection,” published Feb.19, 1999, and incorporate herein by reference.

In certain instances, the handheld device of the present inventioncomprises an array of surface acoustic wave (SAW) sensors, preferablypolymer-coated SAW sensors. The SAW device contains up to six andtypically about four sensors in the array. Optionally, the deviceincludes a preconcentrator with a heater for desorption of the sample.

As will be apparent to those of skill in the art, the sensors making upthe array of the present invention can be made up of various sensortypes as set forth above. For instance, the sensor array can comprise aconducting/nonconducting regions sensor, a SAW sensor, a metal oxide gassensor, a conducting polymer sensor, a Langmuir-Blodgett film sensor,and combinations thereof

FIG. 10 shows various accessories for the e-nose device. A case 1010 isprovided for easy transport of the e-nose device and its accessories. Apower cord 1012 and a car cord 1014 can each interconnects the e-nosedevice to a power source (i.e., a wall socket or car lighter) forrecharging a rechargeable battery within the e-nose device. These cordsalso allow for operation of the e-nose device without the battery. Abracket or stand 1016 holds the e-nose device in the desired position. A(primary or spare) battery 1018 allows the e-nose device to be usedwithout connection to a power source. A serial cable 1020 and an analogcable 1022 are used to interconnect the e-nose device with a personalcomputer and other test equipment. A stylus 1024 is provided for usewith a touchscreen. One or more snouts 1030 can also be provided asspares or for use in a particular set of applications. A sample syringe1032 can be used for collection of test samples.

FIG. 11 is a perspective view of e-nose device 100 shown mountedvertically in an electrical charging station 1108 and coupled to a hostcomputer 1110. Charging station 1108 recharges the rechargeable batteryof e-nose device 100 via electrical contacts 128 (see FIGS. 2A and 2B).E-nose device 100 is also depicted being coupled to host computer 1110via a data line 1120. Host computer 1110 can be used to update e-nosedevice 100 with various information such as the identity of varioustarget vapors to which the device is to be exposed, as well as toretrieve information from the device such as the results of the device'ssample analyses.

FIG. 12A is a diagram of an embodiment of the electrical circuitrywithin e-nose device 100. In an embodiment, the electrical circuitrymeasures the resistances of the arrays of chemically sensitive resistorsmounted on the sensor array devices (see FIGS. 7 through 9) andprocesses those measurements to identify and quantify the test sample.The circuitry is mounted, in part, on the PCB and includes a processor1210, a volatile memory (designated as a RAM) 1212, a non-volatilememory (designated as ROM) 1214, and a clock circuit 1216. In theembodiment in which plug-in sensor module 150 a is used (see FIGS. 2Aand 5), the chemically sensitive resistors are coupled to the electricalcircuitry via mating electrical connectors 552 a and 552 b (see FIG. 5)that are engaged when sensor module 150 a is plugged into e-nose device100 a.

The chemically sensitive resistors used to implement the sensorstypically have baseline resistance values of greater than 1 kilo-ohm(KΩ). These baseline values can vary as much as ±50% over time. Forexample, a particular chemically sensitive resistor may have a baselineresistance that varies between 15 KΩ and 45 KΩ. This large resistancevariability imposes a challenge on the design of the resistancemeasurement circuitry. In addition, the ratio of the change inresistance to the initial baseline resistance, or ΔR/R, which isindicative of the concentration of the analytes, can be very small(i.e., on the order of hundreds of parts per million, or 0.01%). Thissmall amount of change, likewise, imposes a challenge on the design ofthe measurement circuitry. Further, some sensor module embodimentsinclude multiple (e.g., 32) chemically sensitive resistors, and it isdesirable to measure the resistance values of all resistors with minimumcircuit complexity.

FIG. 12B shows an embodiment of a voltage divider network used tomeasure the resistance of a chemically sensitive resistor 1220.Chemically sensitive resistor (Rch) 1220 is coupled in series to areference resistor (Rref) 1222 to form a voltage divider network. In anembodiment, a number of voltage divider networks are formed, one networkfor each chemically sensitive resistor, with each network including achemically sensitive resistor coupled in series to a correspondingreference resistor. The reference resistors are selected to have arelatively low temperature coefficient. In an alternative embodiment, asingle reference resistor is coupled to all chemically sensitiveresistors.

Referring back to FIG. 12A, a power supply 1224 supplies a predeterminedreference voltage (Vref) to the voltage divider networks such that smallchanges in the resistance value of each chemically sensitive resistorcause detectable changes in the network output voltage. By appropriatelyselecting the values of the reference resistors, the electrical currentthrough each chemically sensitive resistor can be limited, for example,to less than about 25 micro amperes (μA). This small amount of currentreduces the amount of 1/ƒ noise and improves performance.

The analog voltages from the resistor divider networks are providedthrough a multiplexer (MUX) 1226 to an analog-to-digital converter (ADC)1230. MUX 1226 selects, in sequence, the chemically sensitive resistorson the sensor module. Optionally, a low-noise instrumentation amplifier1228 can be used to amplify the voltage prior to digitization, toimprove the ADC's performance and provide increased resolution.

In an embodiment, ADC 1230 is a 22-bit (or higher) delta-sigma ADChaving a wide dynamic range. This allows low-noise amplifier 1228 to beset to a fixed gain (i.e., using a single high precision resistor).Commercially available low cost delta-sigma ADCs can reach samplingspeeds as fast as about 1 millisecond per channel.

In one implementation, the reference voltage provided by power supply1224 to the voltage divider networks is also provided to a referenceinput of ADC 1230. Internally, ADC 1230 compares the divider networkoutput voltages to this reference voltage and generates digitizedsamples. With this scheme, adverse effects on the divider network outputvoltages due to variations in the reference voltage are substantiallyreduced.

The digitized samples from ADC 1230 are provided to processor 1210 forfurther processing. Processor 1210 also provides timing signals to MUX1226 and ADC 1230. Timing for the data acquisition can also be providedvia a serial link to the ADC and via select lines of the MUX.

FIG. 12C is a diagram of another embodiment of the electrical circuitrywithin e-nose device 100. In FIG. 12C, four 8-channel multiplexers(MUXes) 1256 a through 1256 d are provided for added flexibility. Theinputs of MUXes 1256 couple to the voltage divider networks (not shown)and the outputs of MUXes 1256 a through 1256 b couple to four amplifiers1258 a through 1258 d, respectively. The select lines for MUXes 1256 areprocessor controlled. The use of external MUXes offer a low ONresistance and fast switching times. The outputs of amplifiers 1258couple to four inputs of an ADC 1260.

Each amplifier 1258 is a differential amplifier having a reference(i.e., inverting) input that couples to a digital-to-analog converter(DAC) 1262. The DC offset of the amplifier is controlled by processor1250 by measuring the offset with ADC 1260 and directing DAC 1262 toprovide a proper offset correction voltage. To account for DC drift(i.e., drift in the baseline resistance of the chemically sensitiveresistor) the offset can be adjusted prior to actual measurement.Further electrical stability is maintained by placing ADC 1260 on-boardand using differential MUXes.

In the embodiments in FIGS. 12A and 12C, amplification is used with thevoltage divider networks to achieve detection of PPM changes inresistance values. It can be shown that a gain of 50 provides detectionof single PPM increments. In FIG. 12C, amplifiers 1258 also match thesignal to be sampled with the full-scale input of ADC 1260. Thismatching is accomplished by subtracting out the DC component (using DAC1262) and amplifying the AC component. Thus, it is possible to detectsingle PPM changes even with a baseline resistance that varies by ±50%.

In FIGS. 12A and 12C, the ADCs used to measure the resistance values canbe implemented using a (i.e., 4-channel) high-resolution delta-sigmaADC. The delta-sigma ADC's high resolution coupled with theabove-described sensor biasing scheme(s) deliver high flexibility andprecision. Presently available delta-sigma ADC can provide 20 bits ormore of effective resolution at 10 Hz and 16 bits of resolution at 1000Hz, with power consumption as low as 1.4 mW.

In an embodiment, the delta-sigma ADC includes differential inputs,programmable amplifiers, on-chip calibration, and serial peripheralinterface (SPI) compatibility. In an embodiment, the ADC internaldifferential MUXes are configured: (1) with respect to ground forincreased effective resolution of the measurement, and (2) configuredwith respect to the reference voltage for high precision measurement,enhanced electronic stability, and to provide a ratiometric measuringmechanism. A status signal from the ADC indicates when the internaldigital filter has settled, thus providing an indication to select thenext analog channel for digitization.

In FIGS. 12A and 12C, processors 1210 and 1260 can be implemented as anapplication specific integrated circuit (ASIC), a digital signalprocessor (DSP), a controller, a microprocessor, or other circuitsdesigned to perform the functions described herein.

One or more memory devices are provided to store program codes, data,and other configuration information, and are mounted adjacent to theprocessor. Suitable memory devices include a random-access memory (AM),a dynamic RAM (DRAM), a FLASH memory, a read only memory (ROM), aprogrammable read only memory (PROM), an electrically programmable ROM(EPROM), an electrically erasable and programmable PROM (EEPROM), andother memory technologies. The size of the memories is applicationdependent, and can be readily expanded as needed.

In an embodiment, the processor executes program codes that coordinatevarious operations of the e-nose device. The program codes includeinteraction software that assists the user in selecting the operatingmodes and methods and to initiate the tests. After the e-nose deviceperforms a test or operation, the user is optionally presented withconcise results. In the embodiment in which the device includes aprocessor and a built-in algorithm, complex functions and capabilitiescan be provided by the device. In other embodiments in which simplifiedelectronics is provided, complex functions and capabilities of thee-nose device are optionally set up and driven from a host computerusing PC based software.

The processors can also be used to provide temperature control for eachindividual sensor array device in the sensor module. In animplementation, each sensor array device can include a back-side heater.Further, the processor can control the temperature of the samplechambers (e.g., chambers 710 a and 710 b in FIG. 7A) either by heatingor cooling using a suitable thermoelectric device (not shown).

After the processor has collected data representing a set of variableresistance measurements for a particular unknown test sample, itproceeds to correlate that data with data representing a set ofpreviously collected standards stored in memory (i.e., either RAM 1212or ROM 1214). This comparison facilitates identification of analytespresent in the sample chamber and determination of the quantity orconcentration of such analytes, as well as detection of temporal changesin such identities and quantities. Various analyses suitable foridentifying analytes and quantifying concentration include principalcomponent analysis, Fischer linear analysis, neural networks, geneticalgorithms, fuzzy logic, pattern recognition, and other algorithms.After analysis is completed, the resulting information is displayed ondisplay 120 or transmitted to a host computer via interface 1232, orboth.

The identification of analytes and the determination of sampleconcentration can be performed by an “analyzer.” As used herein, theanalyzer can be a processor (such as processors 1210 and 1260 describedabove), a DSP processor, a specially designed ASIC, or other circuitsdesigned to performed the analysis functions described herein, Theanalyzer can also be a general-purpose processor executing program codeswritten to perform the required analysis functions.

As noted above, to facilitate identification of specified analytes, thevariable resistance data from the sensors for a particular unknown testsample can be correlated with a set of previously collected standardsstored in memory. These standards can be collected using one of at leasttwo suitable techniques, as described below.

In one technique, a known reference sample is provided to the samplechamber(s). The known sample can be supplied from a small referencecartridge (i.e., located within the e-nose device). The supplies of thisreference sample to the sample chambers can be controlled by a compactsolenoid valve under the control of the processor. An advantage of usinga known reference sample is the ability to control the identity of thereference sample. The cartridge can be replaced periodically.

In another technique, the unknown test sample supplied to the samplechambers can be selectively “scrubbed” by diverting it through acleansing agent (e.g., charcoal). Again, the diversion of the testsample through the cleansing agent can be controlled by the processorvia a compact solenoid valve. An advantage of this variation is that acartridge is not needed. The cleansing agent can be cleanedperiodically, although it may be difficult to ensure that the referencesample is free of all contaminants.

The processors in FIGS. 12A and 12C direct data acquisition, performdigital signal processing, and provide control over serial peripheraldevices (via SPI), I/O devices, serial communications (via SCI), andother peripheral devices. Serial peripheral devices that can becontrolled by the processors include the ADC and DAC, a 32K externalEPROM (with the capability to expand to 64K), a 32K RAM with integratedreal time clock and battery back up, a 2×8-character dot matrix display,and others. I/Os that can be controlled include five separatetemperature probes (four are amplified through amplifiers and are usedfor four independent heater control loops utilizing transistors), ahumidity probe, two push buttons, a green LED, and others. Serialcommunications to external devices is provided by the on-board low powerRS-232 serial driver.

The processors further control the peripheral devices such as thedisplay, the valve assembly, and the pump. The processors also monitorthe input devices (e.g., push button switches 122 in FIG. 2A) andfurther provides digital communication to a host computer via aninterface (e.g., the RS-232 driver) located in the device's housing(e.g., electrical connector 126 in FIG. 2A).

In the embodiment in FIG. 12C, data acquisition includes communicationand/or control over the (i.e., 20 bit) delta-sigma ADC, the 4-channel(i.e., 12-bit) DAC 1262, and the four discrete 8-channel high-speedanalog MUxes 1256.

The on-board memory (i.e., external RAM) is provided for data loggingpurposes. In an embodiment, the memory is organized in blocks of 32K×8bits. In an embodiment, each sample from the ADC is 24 bits and occupiesthree bytes of memory. Thus, each 32K-byte memory block provides storagefor 10,666 samples. If all 32 channels are used for data loggingpurposes, the memory block provides storage for 333 data points/channel.An internal power supply preserves the data stored in the memory and isdesigned with a lifetime of over five years. The ADC sampling rate isprogrammable and the data can be downloaded over the digital RS-232interface to the host computer.

Communication between the on-board processor and the host computer isavailable to configure the device and to download data from or to theoutside world, in real time or at a later time via a number ofcommunication interfaces including, but not limited to, an RS-232interface, a parallel port, an universal serial bus (USB), an infrareddata link, an optical interface and an RF interface. Serialcommunications to the outside world are provided by the on-board lowpower RS-232 serial driver. Communication to the outside world includes,but is not limited to, a network, such as a computer network e.g. theInternet accessible via Ethernet, a wireless Ethernet, a token ring, amodem, etc. A transfer rate of 9600 bits/second can transmitapproximately 400 data points/second, and higher transfer rates can beused.

FIGS. 13A through 13G depict an embodiment of suitable flowcharts of thefunctional steps performed by the e-nose device in implementing themeasurement and analysis procedures outlined generally above. Theseflowcharts show how the e-nose device is initialized and then controlledthrough its various operating modes. In an embodiment, these operatingmodes include: 1) a Target mode, in which the device is calibrated byexposing it to samples of known identity, 2) an Identify mode, in whichthe device is exposed to a samples of unknown identity, and 3) a Purgemode, in which the device is purged of resident samples.

FIG. 13A shows a flow diagram of an embodiment of the main program menuof the e-nose device. Initially, the e-nose device's various electronicelements (i.e., the display and various internal data registers) areinitialized or reset, at a step 1312. A function background subroutineis then executed, at a step 1314. This subroutine is further describedin FIG. 13B.

After executing the function background subroutine, the program proceedsto a step 1316 in which the processor determines whether or notpush-button switch B1 (e.g., switch 122 a in FIG. 2A) is being pressed.If it is, the program proceeds to a step 1318 in which the device'soperating mode increments to the next succeeding mode (i.e., from theTarget mode to the Identify mode). Thereafter, the program returns tostep 1314 and re-executes the function background subroutine. Theincrementing of the device's operating mode continues until it isdetermined in step 1316 that switch B1 is no longer being pressed.

If it is determined at step 1316 that push button B1 is not (or nolonger) being pressed, the program proceeds to a step 1320 in which itis determined whether or not push-button switch B2 (e.g., switch 122 bin FIG. 2A) is being pressed. If switch B2 is not being pressed, theprogram returns via an idle loop 1322 to step 1314 and re-executes thefunction background subroutine. Otherwise, if it is determined at step1320 that push-button switch B2 is being pressed, the program proceedsto implement the selected operating mode. This is accomplished by theflowchart depicted in FIG. 13C. FIG. 13B shows a flow diagram of anembodiment of the function background subroutine (step 1314). At a step1330, signals indicative of the measurements and parameters selected bythe user (i.e., the temperature and humidity within the sample chambersof the sensor module) are read from the ADCs configured to detect theinput devices (also referred to as the internal ADCs). The status of thepush-button switches (e.g., switches 122 a through 122 c FIG. 2A) aredetermined, at a step 1332, based on the signals from the internal ADCs.The signals controlling the heaters located on various sensor arraydevices of the sensor module are then updated, at a step 1334. Signalsindicative of the measurements of the divider networks, formed by thechemically sensitive resistors and their corresponding referenceresistors, are read from the instrumentation ADCs (also referred to asthe external ADCs), at a step 1336. Finally, at a step 1338, theprocessor processes any commands received from the host computer via theserial data line. Such commands can include, for example, programminginformation about the identity of various reference samples to besupplied to the e-nose device during the target operating mode. Thefunction background subroutine then terminates.

FIG. 13C shows a flow diagram of an embodiment of a subroutine fordetermining which one of the operating modes to implement. At a step1340, a determination is made whether or not the selected operating modeis the Target mode. If it is not, a determination is made whether or notthe selected operating mode is the Identify mode, at a step 1342.Typically, the Identify mode is selected only after the target modesubroutine has been implemented for all of the designated targetsamples. If the selected operating mode is the Identify mode, theprogram executes the identify mode subroutine (depicted in FIG. 13E), ata step 1344.

Otherwise, if the selected operating mode is not the Identify mode, adetermination is made whether or not the selected operating mode is thePurge mode, at a step 1346. If it is, the program executes the purgemode subroutine (depicted in FIG. 13F), at a step 1348. Otherwise, theprogram executes the purge target mode subroutine (depicted in FIG.13G), at a step 1350. The purge target mode is the default mode.

Back at step 1340, if it is determined that the selected operating modeis the Target mode, the program proceeds to a step 1352 in which thefunction background subroutine is executed. This provides updated valuesfor the internal and external ADCs, as described above. Thereafter, at astep 1354, it is determined whether or not push-button switches B1 andB2 are being pressed concurrently. If they are, the program does notimplement the Target mode and instead returns to the idle loop (step1322 in FIG. 13A).

Otherwise, if it is determined at step 1354 that both push-buttonswitches B1 and B2 are not being pressed concurrently, the programproceeds to a step 1356 in which it is determined whether or not switchB1 has been pressed. If it has been, the program proceeds to a step 1358in which the particular target number is incremented. In an embodiment,the e-nose device is configured to measure multiple (e.g., eight)different target samples, and step 1358 enables the operator to selectthe particular target sample that is to be drawn into the device formeasurement. The identity of these target samples previously has beenloaded into the device from the host computer. Thereafter, the programreturns to the step 1352 to execute the function background subroutine.Each time it is determined that switch B1 has been pressed, the programcycles through this loop, incrementing through the preloaded complementof target samples.

If it is determined at step 1356 that switch B1 has not been pressed,the program proceeds to a step 1360 in which it is determined whether ornot switch B2 has been pressed. If it has not, the program returns tostep 1352 to execute the function background subroutine. Otherwise, ifit is determined in step 1360 that switch B2 has just been pressed, theprogram proceeds to implement the target mode subroutine (depicted inFIG. 13D), at a step 1362.

FIG. 13D shows a flow diagram of an embodiment of the target modesubroutine. At a step 1370, the most recently updated set ofmeasurements from the external ADC is retrieved. These measurementsrepresent the baseline resistance values of the 32 chemically sensitiveresistors of the sensor module. Next, the pump is conditioned to drawthe designated target sample into the sensor module's sample chamber(s),at a step 1372. A new set of measurements is then retrieved from theexternal ADC, at a step 1374. This new set of measurements indicates theresistance values of the 32 chemically sensitive resistors as theyrespond to the target sample that has been drawn in the samplechamber(s).

At a step 1376, the 32 resistance measurements (i.e., the “responsevector”) for this particular target vapor are normalized. In anembodiment, this normalization set the sum of all 32 measurements equalto a value of 1×10⁶. The normalized response vector for this targetsample then is stored in memory, at a step 1378. Finally, at a step1380, the pump and valve assembly are configured to draw clean air intothe sample chamber(s). The target mode subroutine then terminates, andthe program returns to the idle loop (step 1322 in FIG. 13A).

FIG. 13E shows a flow diagram of an embodiment of the identify modesubroutine. Steps 1390, 1392, 1394, and 1396 in FIG. 13E are similar tosteps 1370, 1372, 1374, and 1376 in FIG. 13D, respectively. At a step1398, the normalized response vector for the unknown sample calculatedin step 1396 is compared with the normalize response vectors for thevarious target samples, as determined by earlier passes through thetarget mode subroutine (FIG. 13D) and stored in memory. Specifically,differences between the respective normalized response vectors arecalculated at step 1398, and the smallest difference vector isdetermined (i.e., using a least mean square analysis), at a step 13100.Also at step 13100, the result of that determination is displayed on adisplay. Finally, at a step 13102, the pump and valve assembly areconditioned to draw clean air to the sample chamber(s). The identifymode subroutine then terminates, and the program returns to the idleloop (step 1322 in FIG. 13A).

FIG. 13F shows a flow diagram of an embodiment of the purge modesubroutine. At a step 13120, the pump and valve assembly are conditionedto draw clean air into the sample chamber(s) via the intake port. Theprogram then returns to the idle loop (step 1322 of FIG. 13A).

FIG. 13G shows a flow diagram of an embodiment of the purge target modesubroutine. At a step 13130, all of the target sample information storedin memory is erased. The program then returns to the idle loop (step1322 in FIG. 13A).

FIG. 14 shows a diagram of an embodiment of the menu selection for thee-nose device. In FIG. 14, a main menu 1408 displays the measurementmodes available for the particular e-nose device. The available modescan be dependent, for example, on the particular modules installed inthe e-nose device. In an embodiment, the following modes are availablein the main menu: Identify, Quantify (Qu), Process Control (PC), DataLogging (DL), Train, and Diagnoses. Upon making a mode selection in menuscreen 1408, a menu screen 1410 appears that queries the user to selecta particular method from among a set of available methods.

By selecting the ID Method option, a menu screen 1412 appears thatqueries the user to press “sniff” to begin identification or “cancel” toreturn to the main menu. Upon selecting the sniff option, the e-nosedevice begins the identification process, as shown in a menu screen1414, and provides the results upon completion of the process, as shownin a menu screen 1416. The user is provided with an option to save theresults.

By selecting the Qu Method option, a menu screen 1420 appears thatqueries the user to select a target. If the identity of the target isunknown, a menu screen 1422 provides the user with the option ofperforming a sniff to identify the unknown target. Upon selecting thesniff option, the e-nose device begins the identification process, asshown in a menu screen 1424, and provides the identity upon completionof the process, as shown in a menu screen 1426. Once the sample isidentified or if the identity is known initially, the target can bequantified in menu screens 1426 and 1428. The e-nose device begins thequantification process, as shown in a menu screen 1430, and provides theresults upon completion of the process, as shown in a menu screen 1432.

By selecting the PC Method option, a menu screen 1440 appears thatqueries the user to press “sniff” to begin the process control or“cancel” to return to the main menu. Upon selecting the sniff option,the e-nose device begins the process control, as shown in a menu screen1442, and provides the status report, as shown in a menu screen 1444.

By selecting the DL Method option, a menu screen 1450 appears thatqueries the user to press “sniff” to begin the data logging or “cancel”to return to the main menu. Upon selecting the sniff option, the e-nosedevice begins the data logging process, as shown in a menu screen 1452,and provides the status report, as shown in a menu screen 1454.

By selecting the Train option, a menu screen 1460 appears that queriesthe user to select one of a number of training methods. The user selectsa particular method and a menu screen 1462 appears that queries the userto select one of a number of targets. The user selects a particulartarget and a menu screen 1464 appears that queries the user to press“sniff” to begin the training. Upon selecting the sniff option, thee-nose device begins the training process using the method and targetselected by the user, as shown in a menu screen 1466.

By selecting the Diagnostics option, a menu screen 1470 appears thatqueries the user to select a diagnostic to run. Possible diagnosticsinclude, for example, RS-232 port, USB port, sensor range test, memory,processor, and program check sum. The user selects a particulardiagnostic and the e-nose device begins the selected diagnostic test, asshown in a menu screen 1472, and provides the diagnostic results, asshown in a menu screen 1474.

Modular Design

In certain aspects of the invention, the e-nose device is designed usingmodular sections. For example, the nose, filter, manifold, sensormodule, power pack, processor, memory, and others can optionally bedisposed within a module that can be installed or swapped, as necessary.The modular design provides many advantages, some of which are relatedto the following characteristics: exchangeable, removable, replaceable,upgradable, and non-static.

With a modular design, the e-nose device can be designed for use in widevariety of applications in various industries. For example, multiplesensor modules, filters, and so on, can be added as the list of samplesto be measured expands.

In certain embodiments, the modular design can also provide improvedperformance. The various modules (i.e., nose, filter, manifold, sensormodule, and so on) can be designed to provide accurate measurement of aparticular set of test samples. Different modules can be used to measuredifferent samples. Thus, performance is not sacrificed by the use of asmall portable e-nose device. For example, to sense high molecularweight analytes, a certain particular nose chip is plugged in. Then, toanalyze lower molecular weight analytes, another nose chip may beplugged in.

The modular design can also result in a cost effective e-nose design.Since some of the components can be easily replace, it is no longernecessary to dispose the entire e-nose device if a particular componentwears out. Only the failed components are replaced.

In certain embodiments, the modular design can also provide anupgradable design. For example, the processor and memory module(individually or in combination) can be disposed within an electronicunit that can be upgraded with new technologies, or as required by onthe particular application. Additional memory can be provided to storemore data, by simply swapping out memory modules. Also, the analysisalgorithms can be included in a program module that inserts into thee-nose device. The program modules can then be swapped as desired.

The modular design can also provide for disposable modules. This may beadvantageous, for example, when analyzing toxic samples.

Nose

In the embodiments described above, the e-nose device includes anexternal sampling wand (or nose or snout). The nose can be attached tothe device using a mechanical interconnect, such as a simple ¼-turntype, a threaded screw, a snap-on mechanical arrangement, and otherinterconnect mechanisms. Many materials can be used to fabricate thenose component, such as injection moldable materials.

In certain embodiments, the nose is interchangeable and uses a standardluer interconnection. The nose can be, for example, about 1 inch toabout 50 inches in length and, preferably, the nose is about 6 inches toabout 20 inches in length. The nose can optionally be ridged, or be along flexi-hose or a flexible snorkel. In some embodiments, the nose hasa luer needle on the smelling end. Optionally, the nose can withstand aninternalized pressure and is joined with a pressured valve.

As shown in FIG. 3B, the nose can be dimensioned in various sizes andshapes. For example, nose 130 d includes a wide opening that may beadvantageous, for example, when sampling a gas. In contrast, nose 130 fincludes a pointed tip that is more suited for sampling at a specificsite.

In some alternative embodiments, intake ports (such as intake port 132)can be used to receive test samples. The intake ports can substitutefor, or supplement the external nose.

Sensor Modules

In certain aspects, the chemically sensitive sensors in the sensormodule can be tailored to be particularly sensitive to particularclasses of vapors. For example, the array for one such module canincorporate vapor sensors suitable for differentiating polar analytessuch as water, alcohol, and ketones. Examples of polar polymers suitablefor use as such vapor sensors include poly (4-vinyl phenol) and poly(4-vinyl pyrrolidone).

The sensor module can optionally be identified by means of anidentification resistor (not shown) having a selected resistance. Thus,prior to processing the variable resistance measurements collected forthe chemically sensitive resistors of each such sensor module, theprocessor measures the resistance of the identification resistor. Inthis manner, the nature of the module's chemically sensitive resistorscan be initially ascertained.

A mechanism for detection of analytes is disclosed in the aforementionedPCT patent application Ser. No. WO99/08105.

Display

In some embodiments, the display is a liquid-crystal display (LCD). Inother embodiments, the display is a graphical LCD that allows the deviceto display text and graphics. This type of display provides a qualityproduct interaction experience. Examples of LCD modules include thosemanufactured by Epson Corporation, such as the EPSON EG7502 (TCM AO822)having a screen size of 57.56 mm by 35.99 mm, a 320×200 resolution with0.8 dot pitch, and transflective and LED edge back light. Various otherLCD modules are also suitable. Preferred LCD modules offer one or moreof the following features: (1) higher resolution to allow for a smallerbut comfortable display viewing areas (320×200 and fine dot pitch), (2)low power consumption (e.g., 3 mW to 9 mW), (3) multi-line scanning(active addressing) technology, (4) integrated “touch” panel, (5)integrated power supply and controller chips, (6) LED baklighting-forsmaller module, (6) displays used with video, and other features.

Input Devices

In certain embodiments, the e-nose device optionally includes inputdevices, such as push buttons, a keypad, a keyboard, a touchscreen,switches, other input mechanisms, or a combination of the above. Thekeypad can be fabricated from various materials. In certain embodiments,the keypad is molded from silicone rubber, which advantageously providestactile feedback for gloved hands. Moreover, navigational controls canoptionally be incorporated into the keypad and buttons. For example, a“sniff” button can be optionally positioned into the keypad.

The keypad can optionally be a membrane type keypad. In thisimplementation, the keypad is formed from laminated sheets of acrylic,Mylar, PC, or other suitable materials. Snap domes can be used toachieve greater tactile feedback for the user. Product graphics can beincorporated into the keypad. Advantageously, the keypad has flexibilitywith graphics, is easy to clean, and has protection from spillage. Inaddition, the keypad is configured with low stroke distances. In certainother instances, a micro-switch, such as for a “sniff” button, is usedto further accentuate the tactile “click” feedback and generate alow-level audible signal.

In certain embodiments, the e-nose device optionally includes a pointer.Advantageously, the pointer provides greater application flexibility andease of use in the field. In certain aspects, the pointer can be usedfor bar code reading and easy inventory control. Further, the deviceoptionally includes a pad. The pad allows for application flexibility,such as in field, training, or lab use.

The e-nose device optionally includes other input devices, such as atouch screen. Suitable touch screens include the analog resistive type.Other touch screens include those similar to the ones in PDA, GPS, andother products. Yet other touch screens include electromagneticresonance types optionally having a dedicated stylus, such as abattery-less stylus. In addition, touch screens can include, but are notlimited to, electrostatic, GSAW, and analog resistive and capacitivetypes. The analog resistive touch screen is preferred since high and lowresolutions can readily be achieved.

In certain embodiments, the e-nose device notifies the user by providinggeneral and specific information about the device's current mode.Operators of the device can see what options are available. Guidelinesand instructions are available to assist the users interact with theproduct. In certain instances, the descriptions and instructions arebrief and specific. Graphics and icons assist users through the productinteraction. Users are provided with a mechanism to stop the device whennecessary, and to return to previous screens where appropriate. Thesevarious features collaborate to provide device interactions that arequick, simple, and reliable.

In other embodiments, the e-nose device provides the users withinformation regarding the status of the device. Examples include, butare not limited to, initiating an action, performing an operation,waiting for input, and so on. Moreover, other device input and outputparameters, such as hardware controls, include, but are not limited to:Scroll Up—keypad; (2) Scroll Down—keypad; (3) Select—keypad; (4) Cancel—keypad; (5) Sniff—keypad; (6) Power-on/Backlight on/off; (7) DigitalInput—connector; (8) Analog Output—connector; (9) Serial out(RS232)—RJ11; (10) USB—Standard A; (11) Display contrast—(thumbwheel,analog pot); (12) System reset—pin hole; (13) Battery recharge—jack;(14) pneumatics ports; (15) nose inhale port (sample sniff port); (16)exhale (exhaust); and (17) reference intake.

Radiocard

In certain aspects, the device has wireless Ethernet capabilities suchas a radiocard having a media access controller. The media accesscontroller regulates the data from handheld device to other devices.

Power Pack

The e-nose device optionally includes a power pack, such as a battery,for providing electrical power. In certain embodiments, the deviceoperates from power supply voltages of approximately 3.3 volts andapproximately 5.0 volts DC. In a specific embodiment, the deviceconsumes approximately 3.2 watts or less, with a typical average powerconsumption of approximately 1.8 watts. In an embodiment, the device iscapable of operation from about 1 hour to about 20 hours withoutrequiring a recharge of the power pack.

The power pack can be fabricated using nickel cadmium (NiCd),nickel-metal hydride (NiMH), lithium ion (Li-ion), sealed lead-acid(SLA), or other battery technologies. Preferably, the battery pack haslow weight and a high power density to keep the volume of the batterysmall. Lithium-ion cells have a relatively high internal resistance andwider range of voltages during a discharge compared to other batterychemistries. A voltage regulator can be used to provide proper voltagesfor the circuitry within the e-nose device. For efficiency, a switchingvoltage regulator can be used in place of linear type regulators. Thevoltage regulator can also be used to provide multiple output voltagesfor different circuitry within the e-nose device. In certain instances,output voltages required from the power supply include values above andbelow the battery voltage. In these instances, a SEPIC topology for theswitching regulator can optionally be used. Conversion efficiency ofsuch switching regulators is approximately 85%. To provide approximately18 watt-hours of energy to the load using such switching regulator, theenergy requirement from the lithium-ion battery pack is approximately 21watt-hours.

In a specific embodiment, a lithium-ion (Li-ion) battery pack ofapproximately 100 cubic centimeters (cc) in volume and about 250 gramsin weight can optionally be used for the e-nose device. In anotherspecific embodiment, a nickel-metal hydride (NiMH) battery pack can beused that weighs about 370 grams and has a volume of about 150 cc. Otherbatteries capable of providing an equivalent amount of energy include,but are not limited to, a nickel-cadmium (NiCd) battery pack ofapproximately 560 grams and 210 cc and a sealed lead-acid (SLA) batterypack of approximately 750 grams and 350 cc.

In general, charging times increase and the available battery capacityreduces for low (e.g., 0 to 10° C.) and high (e.g., 40 to 50° C.)temperatures. For accurate “gas gauging” under such conditions, theSmart Battery System (SBS) can also be employed. The SBS is part of acommercially available System Management Bus (SMB) system. The SBSallows battery packs to communicate to smart chargers and other systemintelligence using a physical protocol similar to the I²C bus protocolfrom Philips Corporation. The software protocol on the SMB allows fordirect communication of parameters such as the state of charge, batterypack voltage, battery temperature, number of discharge cycles, and soon. Several vendors of integrated circuits now offer single chipimplementations of the SMB interface. Alternatively, a custom programmedmicrocontroller, such as a PIC chip Microchip Technology Inc., can beused for this purpose.

In some embodiments, the device includes a power pack that is optionallychargeable. In some other embodiments, the device optionally includesbatteries such as, for example, four AA cells. The cell chemistries canvary. The device optionally accommodates alkaline interchangeability.

The device optionally has a fitting for a secondary rechargeable packthat can be the same, or smaller, size as the power devices describedabove.

Specific Electronic-Nose Device Implementations

The e-nose device can be implemented in various configurations, toinclude various features, and be used in various applications. Somespecific implementations are provided below.

In one specific implementation, the e-nose device includes a sensorarray of 32 sensors, composed of conducting particles uniformlydispersed in a polymer matrix. Each polymer expands like a sponge whenexposed to a test medium (e.g., vapor, liquid, gas), thereby increasingthe resistance of the composite. The polymers expands to varying degreesbecause of their unique response to different analytes. This change inresistance varies across the sensor array, producing a distinctivesignature response. Regardless of whether the analytes correspond to acomplex mixture of chemicals in the test sample or from a singlechemical, the e-nose device includes sufficient polymer arrays toproduce a distinct electrical “fingerprint” for the samples of interest.The pattern of resistance changes in the sensor array is indicative ofthe identity of the analytes, while the amplitude of the patternindicates the concentration of the analytes.

The normalized change in resistance is then transmitted to a processorthat identifies the type, quantity, and quality of the vapor based onthe detected pattern in the sensor array.

In another specific implementation, a portable e-nose device for use inthe field to detect volatile compounds is fabricated according to theinvention. The device incorporates an easy-to-read graphic LCD with backlighting and one or more light emitting diodes (LEDs) to indicate modeof operation. Communications ports are provided to enable easydownloading of data into a spreadsheet package. Rapid response time,combined with easy one-button operation, provide an effective andaccurate measurement of the samples. Power is supplied by replaceable orrechargeable batteries. Housed in a robust, water-resistant case, theportable e-nose device is suitable for various environments.

In yet another specific implementation, the e-nose device is designed toacquire and store data collected from 32 independent sensor elements.The e-nose device includes a 32-channel sample chamber with inlet/outletports, a pump, a 3-way solenoid switch, a LCD, push buttons, LED, ahumidity probe, a temperature probe, and a digital interface. In certainaspects, the temperature probe and the humidity probe can be used tomeasure the environment of the analyte.

The power supply is designed for a 9-volt DC input. A rectifying diodeis added for circuit protection. Two on-board 5-volt linear regulatorsare utilized for the analog and digital circuitry, respectively. A highprecision buried Zener diode is provided to supply a +2.5 voltreference. The overall design is a mixed 3V and 5V design for reducedpower consumption in a handheld device.

The sample chamber houses 32 sensor elements deposited on four ceramicsubstrates, each with eight sensor elements. The substrates arefabricated using hybrid microelectronic co-fired ceramic (alumina)processes. Electrodes and contacts are deposited as thick films usingscreen-printing techniques. Resistive paths can be provided (e.g., threepaths) to be used as heating elements. On the backside of the substrate,a surface mount thermistor can be placed to form a heating/coolingcontrol loop.

An inlet port is provided and a baffle can be inserted to fan out theincoming sample stream. The outlet port is respective to ambientbarometric pressures. The sample chamber can be fabricated of Teflon andis airtight, and is mount to the PCB. An on-board pump can push thesample flow into the sample chamber at pressures slightly higher than14.7 psi. The on-board 3-way solenoid switch can switch under processorcontrol between a known reference source (i.e., to “re-zero” orrecalibrate as necessary) and an unknown test sample. The four ceramicsubstrates are inserted in two 20-pin, 50-mil spacing, dual rowconnectors. The spacing between the rows is 100 mils. A temperatureprobe is inserted into one connector and a humidity probe is insertedinto the other. The temperature and humidity probes are used fordiagnostics.

A biasing network can been implemented that biases the chemicallysensitive resistor in a DC mode of operation. The network is aratiometric network that is easy to implement and stable, and offers awide dynamic range.

It has been shown that 50 PPM changes in electrical resistance of thechemically sensitive can be measured. Further, baseline changes greaterthan ±50% can be accounted for with minimal change in applied power, asshown in Table 1.

TABLE 1 Detectable Changes in Resistance for Various BaselineResistances Baseline Vout Applied Power Resolution 15K (−Δ50%) 0.3260.047 18 bits 20K (−Δ33%) 0.417 0.043 18 bits 25K (−Δ17%) 0.500 0.040 17bits 30K, nominal 0.577 0.037 17 bits resistance 35K (+Δ17%) 0.648 0.03417 bits 40K (+Δ33%) 0.714 0.032 17 bits 45K (+50%) 0.776 0.030 17 bits

Assuming that Johnson noise is the dominant noise source, it is possibleto calculate an average noise voltage of 0.3 μV over a 10 Hz bandwidthand can thus detect these step changes. By keeping the current low(i.e., <25 μA) the 1/ƒ noise is reduced. In general, the biasing schemeis a constant voltage, DC system. The current is limited tomicro-amperes (μAs) per sensor element and the applied power is in theorder of micro-watts (μWs). For added flexibility the current is limitedand the output voltage is scaled by resistors.

The handheld sensing apparatus of the present invention was used tosense a series of four (4) homologous ester analytes. The analytessensed were the ethyl esters of propionate, butyrate, valerate, andhexanoate. The response data was then analyzed using principal componentanalysis. Principal Component Analysis (PCA) is a powerful visualizationtool that provides a way to reduce the dimensionality of the data. PCAfinds linear combinations of the original independent variables thataccount for maximal amounts of variation and provides the best possibleview of variability in the independent variable block. Naturalclustering in the data is readily determined.

FIG. 15 shows a graph of a principal component analysis of the responsesto a series of esters using the handheld apparatus. As shown in FIG. 15,the ester analytes were well discriminated by the handheld device.

Analytes and Applications of the E-Nose Device

Analytes detectable by the e-nose device of the invention include, butare not limited to, alkanes, alkenes, alkynes, dienes, alicyclichydrocarbons, arenes, alcohols, ethers, ketones, aldehydes, carbonyls,carbanions, heterocycles, polynuclear aromatics, organic derivatives,biomolecules, microorganisms, bacteria, viruses, sugars, nucleic acids,isoprenes, isoprenoids, and fatty acids and their derivatives. Manybiomolecules, such as amino acids, are amenable to detection using thesensor arrays of the invention.

The e-nose device can be used to enable medical and dentalcare-providers to quickly and accurately identify the chemicalcomponents in breath, wounds, and bodily fluids to diagnose a host ofillness including infections and metabolic problems. For example, thee-nose device can be used to test for skin conditions, for anesthesiaadministration, or to determine time of ovulation in fertilitytreatment. Moreover, the device can be used in genomic assays andtarget-based pharmaceutical screening. Alternatively, the handhelddevice can classify and identify microorganisms, such as bacteria.

The e-nose device can be used to locate an odor to identify acomplicated system or state of matter, and can offer versatility andreliability absent from conventional environmental or chemicalmonitoring devices. Advantageously, the device can be used for profilinga chemical environment in a hazardous materials situation and to assistemergency crews to accurately select fire retardant, containmentstrategies, and protective gear. The e-nose device can be used to detectleaks in pipelines and storage containers.

The e-nose device can be used in food quality and processing control.For example, the device can be used to spot test for immediate resultsor to continually monitor batch-to-batch consistency and spoilage invarious stages of a product, including production (i.e., growing),preparation, and distribution. The device can also be used in disposablepackaging to providing an objectivity that is absent from conventionalspoilage, freshness, and contamination monitoring techniques.

The e-nose device can also be used in protecting the elderly, who tendto lose sense of smell over time. The device can be used to reduce therisk of food poisoning or the ingestion of spoiled food, and can beintegrated with household appliances, such as refrigerators andmicrowave ovens.

The e-nose device can be used in a wide variety of commercialapplications including, but not limited to:

-   -   applications such as utility and power, oil/gas petrochemical,        chemical/plastics, automatic ventilation control (cooking,        smoking, etc.), heavy industrial manufacturing, environmental        toxicology and remediation, biomedicine, cosmetic/perfume,        pharmaceutical, transportation, emergency response and law        enforcement,    -   detection, identification, and/or monitoring of combustible gas,        natural gas, H₂S, ambient air, emissions control, air intake,        smoke, hazardous leak, hazardous spill, fugitive emission,        hazardous spill,    -   beverage, food, and agricultural products monitoring and        control, such as freshness detection, fruit ripening control,        fermentation process, and flavor composition and identification,    -   detection and identification of illegal substance, explosives,        transformer fault, refrigerant and fumigant, formaldehyde,        diesel/gasoline/aviation fuel, hospital/medical anesthesia &        sterilization gas,    -   telesurgery, body fluids analysis, drug discovery, infectious        disease detection and breath applications, worker protection,        arson investigation, personal identification, perimeter        monitoring, fragrance formulation, and    -   solvent recovery effectiveness, refueling operations, shipping        container inspection, enclosed space surveying, product quality        testing, materials quality control, product identification and        quality testing.

The e-nose device 100 can be used to detect and capture analyte data andsubsequently transmit such data to the outside world over a computernetwork for analysis at a remote location. FIG. 16 is a simplifiedschematic block diagram showing one mode of operation of the presentinvention. In this mode of operation, the e-nose device 100 detects ananalyte 16 and subsequently transmits the data relating to such analytevia a computer network 18 to the processor 12 for analysis. The datacommunications between the e-nose device 100 and the processor 12 can beeither one-way or two-way communication. The e-nose device 100 can actsolely as a transmitter capable of only sending data to the processor12, or alternatively, the e-nose device 100 can act as a transceivercapable of both sending and receiving data from the processor 12. Inaddition, e-nose devices 100 may also be able to communicate with oneand other.

The processor 12 includes a processor interface 24 and an analyteanalyzer 26. The main function of the processor interface 24 is tohandle data communications between the processor 12, the e-nose device100 and the electronic library 14. The processor interface 24 receivesdata from the e-nose device 100 via the computer network 18 andprocesses the data into a format that can be understood by the analyteanalyzer 26. When necessary, the processor interface 12 also interactswith the electronic database 14 to retrieve data therefrom foranalytical purposes or update the electronic database 14 with new data.

The analyte analyzer 26 is capable of performing analysis on a detectedanalyte. Using data stored in the electronic library 14, the analyteanalyzer 26 compares data received from the e-nose device 100 with dataretrieved from the electronic database 14 via the processor interface 24to identify the identity of the detected analyte.

The method and system of the present invention include the use ofpattern recognition algorithms to compare the output signature of thedetected unknown analyte to the signatures of known analytes. Many ofthe algorithms are neural network based algorithms. A neural network hasan input layer, processing layers and an output layer. The informationin a neural network is distributed throughout the processing layers. Theprocessing layers are made up of nodes that simulate the neurons by itsinterconnection to their nodes.

In operation, when a neural network is combined with a sensor array, thesensor data is propagated through the networks. In this way, a series ofvector matrix multiplications are performed and unknown analytes can bereadily identified and determined. The neural network is trained bycorrecting the false or undesired outputs from a given input. Similar tostatistical analysis revealing underlying patterns in a collection ofdata, neural networks locate consistent patterns in a collection ofdata, based on predetermined criteria.

Suitable pattern recognition algorithms include, but are not limited to,principal component analysis (PCA), Fisher linear discriminant analysis(FLDA), soft independent modeling of class analogy (SIMCA), K-nearestneighbors (KNN), neural networks, genetic algorithms, fuzzy logic, andother pattern recognition algorithms. In a preferred embodiment, theFisher linear discriminant analysis (FLDA) and canonical discriminantanalysis (CDA) and combinations thereof are used to compare the outputsignature and the available data from the electronic library. Theoperating principles of various algorithms suitable for use in thepresent invention are disclosed (see, Shaffer et al., Analytica ChimicaActa, 384, 305-317 (1999)), the teaching of which are incorporatedherein by reference.

With respect to the electronic library 14, it generally containssignatures for various known analytes and other relevant informationpertaining to these analytes. The electronic library 14 can be composedof a number of different databases. These databases can be located inone central depository, or alternatively, they can be dispersed amongvarious distinct physical locations. These databases can be categorizedand structured in various ways based on the needs and criteria of thedatabase designer. For example, a first database may contain datarelating to various types of analytes collected using the same detectiontechnique under a standardized set of conditions, and a second relateddatabase may contain miscellaneous information correlating to datacontained in the first database. Alternatively, a database may containdata specific to one particular analyte with such data collected usingdifferent detection techniques. Methods used to create and organizedatabases are commonly known in the art, for example, relationaldatabase techniques can be used to logically connect these databases.

The databases comprising the electronic library 14, or a portionthereof, can be physically located separate from the processor 12. Thesedatabases can reside on remote, distant servers on a local area networkor the Internet. Under this arrangement, whenever any data are needed,the processor 12 needs to access the necessary database(s) via acommunication channel to retrieve the requisite data for analysis. Forexample, the processor 12 can access and retrieve data from a remotedatabase via a computer network such as a LAN or the Internet.

A number of different technologies can be used to implement thecommunications between the e-nose device 100, the processor 12 and theelectronic library 14. As to communications between the e-nose device100 and the processor 12, such communications can be conducted via acomputer network 18. The computer network 18 can be one of a variety ofnetworks including a worldwide computer network, an internet, theInternet, a WAN, a wireless network, a LAN or an intranet. It should beunderstood that conventional access to the computer network is conductedthrough a gateway (not shown). A gateway is a machine, for example, acomputer that has a communication address recognizable by the computernetwork 18.

The e-nose device 100 can communicate to the outside world via acomputer network 18 using either wireless or wired technologies.Wireless technologies may include infrared, radio waves, and microwaves.Wired technologies may include cables and modems. For example, as shownin FIG. 17, the e-nose device 100 can be detachably coupled to a dockingdevice 30 which, in turn, is connected to a gateway on the computernetwork 18.

Furthermore, as mentioned above and shown in FIG. 18, e-nose devices 100may be able to communicate with one another directly. In thisdevice-to-device type of communication, infrared signals are generallyused.

As to communications between the processor 12 and the electronic library14, the communications can also be conducted via a computer network. Asmentioned above, depending on various requirements, the electroniclibrary 14 can reside on the same machine as the processor 12, therebyreducing communication overhead and costs.

The e-nose device 100 generally performs the following steps before thecaptured analyte data are delivered to the computer network 18 fortransmission: (1) capturing analyte data in analog form; (2) convertingthe analog data into electrical data; (3) encoding electrical data intoan analysis format; (4) encoding data in analysis format into a TCP/IPformat; and (5) encoding data in TCP/IP format into a specific networkdata format. At the receiving end, the processor 12 generally performsthe following steps to decode the encoded data: (1) receiving data inspecific network data format; (2) decoding the received data into TCP/IPformat; and (3) decoding the data in TCP/IP format into an analysisformat.

Details of these steps will now be described with reference to FIGS. 19and 20. FIG. 19 illustrates the various data encoding formats needed toconvert the analog data from the detected analyte into a transmissibleformat for transmission to the processor 12. At step 40, analog datafrom the detected analyte are first captured by the e-nose device 100.The analog data are converted into electrical signals at step 42. Atstep 44, the electrical signals are encoded into an analysis format thatcan be understood by the analyte analyzer 26. This format can be eitherproprietary or well-known. Any format can be used as long as the analyteanalyzer 26 is capable of handling such format. While it is notnecessary that the format used by the e-nose device 100, the processor12, and the electronic library 14 be the same, a standardized format ispreferred since format-conversion overhead can be saved. At step 46, theformatted data are further encoded into a format that can be transmittedover the computer network 18, such as the TCP/IP format. This step 46 isimportant if the formatted data are to be sent to the processor 12 via acomputer network 18, such as the Internet, which contains numeroussub-networks having different network data formats. At step 48, the datain TCP/IP format are encoded into the specific network data format thatthe gateway to the computer network 18 can understand.

FIG. 20 illustrates the various data decoding formats needed to convertthe transmitted data received from the e-nose device 100 to permitanalysis by the processor 12. At step 50, data transmitted from thee-nose device 100 via the computer network 18 are received by thegateway in a network data format specific to the gateway. At step 52,the data in the network data format are decoded into the TCP/IP format.At step 54, the data in TCP/IP format are further decoded into ananalysis format that can be used by the analyte analyzer 26 foranalysis.

In another mode of operation, e-nose devices 100 are capable ofcommunicating and exchanging data with one another. The primary purposehere is to allow sharing of data between two e-nose devices 100. In theevent that multiple e-nose devices 100 (employing the same detectiontechnique) are used to detect the same unknown analyte, data collectedfrom these devices 100 can be used by the processor 12 for calibrationpurposes to provide for any use-to-use variability of a e-nose device100.

In an alternate embodiment, as shown in FIG. 17, certain components ofthe processor 12, such as the analyte analyzer 26, can reside within thee-nose device 100. The analyte analyzer 26 is included within the e-nosedevice 100 as opposed to the processor 12 and the e-nose device 100further includes a data storage area 32. With this particularconfiguration, the present invention may be operated in the followingmanner. The user enters a request 34 into the e-nose device 100 for datarelating to certain specified, known analytes. The e-nose device 100then transmits the request 34 to the processor 12. The processor 12, inturn, retrieves the relevant data from the electronic library 14 inaccordance with the request 34 and forwards the requested data to thee-nose device 100. Upon receipt of the requested data, the e-nose device100 stores them in a data storage area 32 for subsequent use. When thee-nose device 100 is used to detect an unknown analyte 16, data in thedata storage area 32 are readily available for use by the analyteanalyzer 26 to compare and identify the detected analyte 16.

By having the analyte analyzer 26 and the data storage area 34incorporated into the e-nose device 100, the time required for analysiscan be shortened. For example, prior to entering a particular area, ifthe user knows that there is a relatively high probability of presenceof certain known analytes in that area, the user can download thesignatures of these known analytes onto the e-nose device 100 ahead oftime. With the signatures readily available within the e-nose device100, the output signature of the detected analyte 16 can be comparedagainst these known signatures first. Therefore, there may not be a needto connect to the processor 12 thereby allowing the analysis to beperformed more quickly. Connection to the processor 12 only needs to bemade when none of the downloaded signatures matches with that of thedetected analyte 16.

It should be appreciated from the foregoing description that the presentinvention provides an apparatus for detecting and transmitting sensorydata of analytes over a computer network. Although the invention hasbeen described in detail with reference to the presently preferredembodiments, those of ordinary skill in the art will appreciate thatvarious modifications can be made without departing from the invention.Accordingly, the invention is defined only by the following claims.

1. A method for transferring sensory data over a computer network for adiagnostic purpose, wherein said sensory data relates to identifyingcomponents in wounds and body cavities, said method comprising:transmitting sensory data from a sensory device to a remote location;receiving said sensory data at said remote location; and processing saidsensory data at said remote location for diagnostic purpose.
 2. Themethod of claim 1, wherein said sensory device is a handheld device. 3.The method of claim 1, wherein said computer network is a memberselected from a group consisting of a wide area network, a local areanetwork, an intranet, a worldwide computer network, and the Internet. 4.The method of claim 3, wherein said computer network is a wirelessnetwork.
 5. The method of claim 4, wherein the wireless network isimplemented using technologies selected from the group consisting ofinfrared, radio waves, satellite and microwaves technologies.
 6. Themethod of claim 1, wherein said sensory data is a member selected from agroup consisting of physical, chemical, taste, olfaction, opticalolfaction, optical parameters or combinations thereof.
 7. The method ofclaim 1, wherein said sensory data relates to genomic assays andtarget-based pharmaceutical screening.
 8. A system for perimetermonitoring from a plurality of different remote locations to bedistributed over a computer network, said system comprising: a sensorydevice for measuring sensory data at the different locations that iscoupled to said computer network, wherein said sensory device comprisesat least one sensor which is a member selected from the group consistingof a conducting/nonconducting regions sensor, a quartz microbalancesensor, a conductive composite sensor, a chemiresistor and a fiberoptical chemical sensor; and a wireless communication interface coupledto said sensory device and configured to communicate with said computernetwork situated at a remote location.
 9. The system of claim 8, whereinsaid wireless communication interface is selected from the groupconsisting of an infrared data link, an optical interface, a microwavelink and an RF interface.
 10. The system of claim 9, wherein saidwireless communication interface is an RF interface.
 11. The system ofclaim 8, wherein said sensory device is a portable device.
 12. Thesystem of claim 8, wherein said sensory device comprises an analyteanalyzer.
 13. The system of claim 8, wherein said computer networkcomprises an analyte analyzer.
 14. The system of claim 8, whereinsensory data selected from the group consisting of physical, chemical,taste, olfaction, optical parameters or combinations thereof.
 15. Thesystem of claim 8, wherein said sensory device is capable of detectingchemical, biological or explosive analytes.
 16. The system of claim 8,wherein said system for perimeter monitoring is useful for thedetection, identification, and monitoring of a combustible gas, naturalgas, H₂S, ambient air, emissions control, air intake, smoke, a hazardousleak, a hazardous spill and a fugitive emission.
 17. The system of claim8, wherein said system for perimeter monitoring is useful for thedetection and identification of illegal substances, explosives, atransformer fault, a refrigerant, a fumigant, formaldehyde, diesel fuel,gasoline fuel, aviation fuel, medical anesthesia and sterilization gas.18. The system of claim 8, wherein said system for perimeter monitoringis useful for infectious disease detection.
 19. The system of claim 8,wherein said system for perimeter monitoring is useful for shippingcontainer inspection and enclosed space surveying.
 20. The system. ofclaim 8, wherein said system for perimeter monitoring is suitable forthe monitoring and control of beverage, food and agricultural products.21. A system for detection and identification of explosives from aplurality of different remote locations to be distributed over acomputer network, said system comprising: a sensory device for measuringsensory data at the different locations that is coupled to said computernetwork wherein said sensory device comprises at least one sensor whichis a member selected from the group consisting of aconducting/nonconducting regions sensor, a quartz microbalance sensor, aconductive composite sensor, a chemiresistor and a fiber opticalchemical sensor; and a wireless communication interface coupled to saidsensory device and configured to communicate with said computer networksituated at a remote location.
 22. A system for perimeter monitoringfrom a plurality of different remote locations to be distributed over acomputer network, said system comprising: a sensory device for measuringtaste or flavor at the different locations that is coupled to saidcomputer network; and a wireless communication interface coupled to saidsensory device and configured to communicate with said computer networksituated at a remote location.